Explanation
Correct answer: B.
Choice B is the best answer because it most accurately describes how the underlined portion functions in the text as a whole. The first sentence presents the general claim that industrial activity is not always a threat to wildlife. The underlined portion of the sentence that follows suggests that the silver-studded blue butterfly is an example of wildlife thriving in areas of industrial activity: active limestone quarries. Thus, the function of the underlined portion is to introduce a specific example in support of the general claim in the previous sentence.
Why the other choices are wrong
Choice A
Choice A is incorrect. Although the first sentence indicates that “industrial activity is often assumed” to harm wildlife, in the case of the silver-studded blue butterfly the text mentions neither an assumption about this species nor any challenge to such an assumption.
Choice C
Choice C is incorrect because the text mentions only one study: the “survey.” Additional studies are not mentioned in the text.
Choice D
Choice D is incorrect because neither the underlined portion nor any other portion of the text provides a definition for any of the terms used in the text’s argument.